Heat treatment of metallic workpieces



June 1956 J. A. REDMOND ET AL HEAT TREATMENT OF METALLIC WORKPIECES 2 Sheets-Sheet 1 Filed June 19, 1953 Fig. l.

Fig.2.

INVENTORS John A. Redmond 8 Edward J. Garbo BY ATTORNEY Wf arm 2 Sheets-Sheet 2 J. A. REDMOND ET AL HEAT TREATMENT OF METALLIC WORKPIECES N //////////////////lr/ 6 June 26, 1956 Filed June 19, 1953 INVENTORS John A. Redmond 8 Edward J. Curbo BY? ATTORNEY Fig.3.

United States Patent HEAT TREATMENT OF METALLIC WORKPIECES John A. Redmond, Baltimore, and Edward J. Carbo,

Towson, Md., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 19, 1953, Serial No. 362,787

7 Claims. (Cl. 21910.43)

Our invention relates to apparatus and a method for the induction heat treatment of metallic workpieces, and more particularly, to the heat treatment of metallic cartridge or shell cases made of steel or like material.

A metallic workpiece such as a steel cartridge case has an internal radius on the inside surface of the shell case head portion, which internal radius is preferably subjected to heat treatment operation. In accordance with the prior art teachings for accomplishing the heat treatment of this internal radial surface, it was the practice to induction heat treat the entire head portion of the shell case from the outside or exterior of the shell case and subsequently quench from the inside of the shell case the inner radial surface which it is desirable to harden. This prior art heat treatment was objectionable from par ticularly the standpoint of subsequent machine operations, in that by heating the entire head and subsequently quenching the internal surface of the cartridge case which it was desired to harden, the steel in the remainder of the head portion was subjected to a heat treatment which resulted in the outside of the head portion being heat treated such that any subsequent machine operations on particularly this portion of the cartridge or shell case became considerably difficult.

In accordance with the teachings of the prior art, the internal radius of the steel cartridge case which it is desired to heat treat and harden was heated by conduction only and not by induction heat treatment. Accordingly, one of the principal advantages of induction heat treatment, namely quicker operation and speed was lost since considerable time is required for the heat to be introduced to the external surface of the cartridge case head portion and to allow this heat energy to conduct inwardly through the cartridge case to bring the temperature of the internal radial surface up to the required temperature for the desired heat treatment operation. Also, relative slow conduction heat treatment was necessary to prevent overheating the external surface of the cartridge case and an intricate inductor coil design was required for the prior art external heat treatment to prevent objectionable burning of particularly the projecting extractor lip of the cartridge case. In the actual practice of the prior art, even under ideal conditions, the external surface of the cartridge case had to be heated to nearly 2,000 P. for a 90 millimeter or 105 millimeter cartridge case having about a /2 metal cross section adjacent the internal radial surface which it was desired to heat treat. This 2,000 P. temperature of the external surface of the cartridge case resulted in considerable grain growth which was very objectionable and also heated the entire cartridge case head portion to produce a heat treated'external metallurgical structure which was considerably difficult to machine, and more difficult to machine than the original metallic structure.

Accordingly, it is an object of our invention to provide an apparatus and method for heat treating metallic workpieces, and more particularly, for heat treating predetermined portions of such workpieces.

It is a further object of our invention to provide an improved method and apparatus for quench hardening preselected portions of metallic objects such as steel cartridge or shell cases and the like.

It is an additional object of our invention to provide a method and apparatus for heat treating metallic cartridge cases from the inside of those cartridge cases.

it is a still additional object of our invention to provide a simplified apparatus employing an improved inductor member design and arrangement for the heat treatment of metallic workpieces such as cartridge or shell cases and the like.

It is still another object of our invention to provide an apparatus and method for heat treating a preselected inner radial surface of particularly a metallic cartridge case wherein the exterior of the cartridge case and the extractor lip of the cartridge case are not objectionably heated when the said inner radial surface is brought up to the required temperature.

It is another object of our invention to provide an apparatus and method for heat treating and quenching a metallic cartridge case from the inside thereof, wherein a preselected internal radial surface of that cartridge or shell case is given a desired heat treatment or hardness pattern.

It is a still further object of our invention to induction heat treat a metallic workpiece from the inside of that workpiece and to thereby provide an improved resultant heat treatment pattern in less time than required by prior art apparatus and methods of heat treatment.

Other objects and features of our invention will be apparent from the following description and accompanying drawings.

While in the accompanying drawings and description there is illustrated and described our invention as applied to certain specific purposes, it will be readily understood that our invention should not be limited to the particular construction and use shown and described. From the disclosure herein obviously many modifications and other uses will readily suggest themselves to those skilled in the art.

Figure l is a vertical section view of the heat treatment apparatus in accordance with our invention;

Fig. 2 is a perspective view of the heat treatment apparatus in accordance with our invention; and

Fig. 3 is a vertical section view showing a modified form of the invention.

In Fig. 1 there is shown a workpiece positioned for heat treatment by the apparatus and methods of our invention, which workpiece is illustrated as a metallic cartridge or shell case 2. This cartridge case is supported by a support member 4, which support member 4 may be adapted to rotatably support the workpiece relative to the axis of the workpiece. An annular inductor member 6 is shown positioned for the heat treatment of particularly that portion of the cartridge case 2 which is adjacent an internal radial surface 7 of the cartridge case 2. A non-magnetic quench member 8 made of electrically insulating material is provided to support the annular inductor member 6 reiative to the cartridge case 2. The axes of the cartridge case 2, the annular inductor memher 6 and the quench member 8 all coincide. A coupling or connection member 10 is fastened to an end member 12 of an inner concentric high frequency power supply conductor or lead 14, which coupling member 10 physically connects between the quench member 8 and the end member 12, such that the annular inductor member 6 and the quench member 8 are supported in position by the inner concentric high frequency power supply conductor 14 and the outer concentric high frequency power supply conductor 16. An insulation member 18 comprising a layer or the like of electrically insulating material is positioned between the inner concentric high frequency power supply conductor 14- and the outer concentric power supply conductor 16. Quenching fluid or medium is supplied to the quench member 8 through a passage in the interior of the inner concentric power supply conductor 14, and then through the coupling or connection member 10. Coolant fluid for the annular inductor member 6 is supplied through provided coolant fluid conductors or channels 20 and 22, which coolant fluid conductors or channels further provide the electrical connection between the pair of concentric high frequency power supply conductors 14 and 16 and the annular inductor member 6.

An inductor support member 21 is shown in Fig. 1, which support member 21 may be positioned to support the inductor member 6 relative to the power supply conductors 14 and 16. When the inductor support member 21 is so positioned and employed, the quench member 8 may be efiective to hold the inductor member 6 and the support member 21 therefor, relatively positioned as desired. However, the support member 21 may not be used,in which case the quench member 8 supports the inductor member 6.

In Fig. 2 a perspective view of the heat treatment apparatus of Pig. 1 is shown. As more clearly shown in Fig. 2, the quench member 8 is provided with suitable quench fluid or medium openings in its upper surface for the application of quench fluid to the desired inner portions of the workpiece or cartridge case 2 during the heat treatment thereof or subsequent to that heat treatment operation as desired. The annular inductor member is shown in Fig. 2 in its position around the upper portion of the quench member 8, with its axis coincident with the axis of the quench member 8 and the axis of the concentric power supply structure including the inner power supply conductor 14 and the outer power supply conductor 16.

In Fig. 3 is shown a modified form of our invention wherein a quench member 9 is provided, which quench member 9 may be made of powdered iron or like material if desired to increase the efliciency of the heat treatment operation. Also, the quench member 9 may be made of laminated material or the like. An inductor coil 6 is shown supported by the quench member 9 relative to the workpiece 2 to be heat treated. The quench member 9 has a cut-away portion corresponding to the position of the coolant conductors 2t and 22. The quench fluid is operative to cool the quench member 9 in this embodiment.

In accordance with the apparatus and method of our invention, the steel shell cases 2 are induction heat treated and quench hardened from the inside of those shell cases. The projecting extractor lip 5 of the shell case is shown in Fig. l. The annular inductor member 6 and the quench member 8 are coaxially positioned relative to the axis of the shell case 2. Concentric positioned inner and outer power supply conductors l4 and 16 have been provided, which are coaxial in position relative to the axis of the shell case 2 such that the inductor member 6, the quench member 8 and the power supply conductors 14 and 16 can be inserted into a stationary supported shell case 2 or the shell case 2 can be moved into position relative to the stationary positioned heat treatment and quench apparatus, or to allow any combination of relative movement between the workpiece 2 and the heat treatment assembly, including the inductor member 6, the quench member and the power supply conductors 14 and 16, as desired. The concentric power supply conductors or lead structure has the advantage of extremely low impedance and low loss characteristics, which make it practical to run several feet of such a power supply conductor structure into the shell case as necessary.

The inductor member 6 comprises but a single turn, with the ends of that inductor member 6 being separated by a layer of insulation material 24, and which ends are respectively connected to the coolant fluid supply through conductors 20 and 22. The inner power supply conductor 14 is employed as a channel for the quenching fluid to supply the quench fluid to the quench member 3 through the coupling member 10. It should be readily apparent that a variety of different types of quench members 8 and of different types of inductor members 6 may be used with the apparatus and method of our invention as required by the particular internal surface of the workpiece which is to be heat treated.

In accordance with our invention the quench member 8 may be constructed of non-magnetic but electrically conductive material, with the additional provision of electrically insulating material between the quench member 8 and the inductor member 6. Further, a multiple turn inductor member may be employed if considered desirable for any particular workpiece to be heat treated.

Also, it should be readily apparent that other apparatus and method of applying the principles of our invention may be employed instead of those explained and that various changes and modifications may be made as regards the apparatus and steps herein disclosed.

We claim as our invention:

1. In apparatus for the high frequency heat treatment of a metallic cartridge case, said cartridge case including a cylindrical body portion having an axis and a head portion connected to said body portion with an internal radius being provided at the connection of the head portion to the body portion of said case, the combination of an annular inductor member shaped to heat treat said internal radius, and adapted to be positioned inside said body portion and adjacent said head portion, high frequency power supply leads connected to said inductor member and positioned along the axis of the cartridge case body portion, and coolant fluid members connected to said inductor member and adapted to supply a coolant fluid to said inductor member, said coolant fluid members being positioned substantially parallel to said body portion axis.

2. In apparatus for the high frequency heat treatment of a steel shell case, said shell case including a cylindrical body portion having an axis and a head portion integrally fastened to said body portion at an annular junction, with said head portion being positioned substantially perpendicular relative to said axis, thereby providing an internal radial surface at said junction the combination of an annular inductor member adapted to be positioned inside said body portion adjacent said head portion and being shaped to eifect the heat treatment of said radial surface, said annular inductor member having an axis which coincides in position with the body portion axis when the inductor member is in position to heat treat said shell case, high frequency power supply conductors connected to said inductor member and being positioned substantially parallel to the axis of said annular inductor member, and coolant medium conductors connected to said inductor member for the provision of a coolant medium to said inductor member, with each of the coolant medium conductors being fastened to one of said power supply conductors, and being positioned substantially parallel to said power supply conductors.

3. The apparatus of clairn 2 in which the power sup ply conductors have an end portion spaced from said inductor member, and the coolant medium conductors extend between said end portion and the inductor member.

'4. In apparatus for the high frequency heat treatment of a metallic shell case, said shell case including a cylindrical body member having an axis and a head member with a portion of said head member being fastened to a portion of said body member, with said head member being positioned substantially perpendicular relative 19 the axis of said body member, the combination of an annular inductor member adapted to be positioned inside said body portion and adjacent said head portion and being shaped to effect the heat treatment of the portion of said head member and the portion of said body member, said inductor member having an axis which coincides in position with the body portion axis when the inductor member is in position for the heat treatment of said metallic shell case, high frequency power supply conductors connected to said inductor member and positioned substantially parallel to the axis of said inductor member, and coolant medium conductors connected to said inductor member to supply a coolant medium to said inductor member, said coolant medium conductors being electrically connected between the inductor member and the power supply conductors.

5. In apparatus for the high frequency heat treatment of a metallic workpiece, said workpiece including a cylindrical body portion having an axis and a head portion fastened to said body portion and being positioned substantially perpendicular relative to said body portion axis, said head portion having an inner radial surface, in a heat treating unit, the combination of an annular inductor member adapted to be positioned inside said body portion and adjacent the inner radial surface of said head portion, said annular inductor member having an axis, an inner and an outer concentric power supply conductor connected to energize said inductor member and adapted to be positioned substantially parallel to the axis of that inductor member, coolant medium channels connected to said inductor member to supply a coolant medium to said inductor member, and a quench member having an axis and being symmetrical about said axis, said quench member being physically connected between said inductor member and said inner concentric power supply conductor such that a quench path is thereby provided for a quenching medium, said path including the inner concentric power supply conductor and the quench member, with the axis of said quench member being coincident in position with the axis of the inductor member.

6. The apparatus of claim 5, with a workpiece support member, said support member being operable to efiect relative rotation between said workpiece and said inductor member.

7. The apparatus of claim 5, wherein the quench member is made of a non-magnetic insulating material.

References Cited in the file of this patent UNITED STATES PATENTS 2,182,341 Hulster Dec. 5, 1939 2,241,431 Somes May 13, 1941 2,319,093 Somes May 11, 1943 2,358,834 Somes Sept. 26, 1944 2,378,890 Abe et al June 26, 1945 2,556,243 Vaughn June 12, 1951 FOREIGN PATENTS 635,421 Great Britain Apr. 12, 1950 

1. IN APPARATUS FOR THE HIGH FREQUENCY HEAT TREATMENT OF A METALLIC CARTRIDGE CASE, SAID CARTRIDGE CASE INCLUDING A CYLINDRICAL BODY PORTION HAVING AN AXIS AND A HEAD PORTION CONNECTED TO SAID BODY PORTION WITH AN INTERNAL RADIUS BEING PROVIDED AT THE CONNECTION OF THE HEAD PORTION TO THE BODY PORTION OF SAID CASE, THE COMBINATION OF AN ANNULAR INDUCTOR MEMBER SHAPED TO HEAT TREAT SAID INTERNAL RADIUS, AND ADAPTED TO BE POSITIONED INSIDE SAID BODY PORTION AND ADJACENT SAID HEAD PORTION, HIGH FREQUENCY POWER SUPPLY LEADS CONNECTED TO SAID INDUCTOR MEMBER AND POSITIONED ALONG THE AXIS OF THE CARTRIDGE CASE BODY PORTION, AND COOLANT FLUID MEMBERS CONNECTED TO SAID INDUCTOR MEMBER AND ADAPTED TO SUPPLY A COOLANT FLUID TO SAID INDUCTOR MEMBER, SAID COOLANT FLUID MEMBERS BEING POSITIONED SUBSTANTIALLY PARALLEL TO SAID BODY PORTION AXIS. 